Tempo:
In addition, the floors, walls and roofs of wood-frame buildings are meant to act as a structural unit. This is why the floor must be bolted to the concrete foundation. Additional connections are also required between the roof or floors and walls and between the walls and the foundations to provide a continuous and complete load path, especially in high exposure category areas for wind or earthquake.
RESISTANCE TO LATERAL LOADS DUE TO WIND AND EARTHQUAKE Different areas of Canada are subject to varying risks of forces from winds and earthquakes. As a result, all buildings must be built to resist these lateral loads. The NBC Appendix C, Climatic and Earthquake Information for Building Design in Canada, provides wind pressures and earthquake factors used to determine exposure to wind and seismic (earthquake) loads for buildings. NBC 9.23 provides requirements for resisting lateral loads for low-rise buildings. The requirements are based on three levels of risk: low to moderate; high; and extreme.
Low to Moderate Exposure Category Buildings in the low to moderate exposure category provide resistance to wind and earthquake loads if they are of traditional wood-frame construction comprised of exterior sheathing, panel-type cladding or gypsum board finish. If two or more of these options are chosen, lateral load resistance will be increased. Of the 680 locations identified in NBC Appendix C, 671 and 630 locations fall into this category for wind and earthquake exposure respectively. This means that for most locations in Canada, bracing requirements can be met by using standard wood-framing materials and fastening
methods. One can also opt to design according to NBC Part 4 or follow good engineering practices such as those in the Engineering Guide for Wood Frame Construction 2009 published by the Canadian Wood Council.
High Exposure Category Buildings in the high exposure category require additional features to provide the required resistance to lateral loads. Nineteen locations identified in NBC Appendix C fall into this category for wind and 33 for earthquake exposure. For wind, affected locations are in Newfoundland, Quebec, Alberta, Nunavut and the Northwest Territories. Most of the locations affected by earthquake risk are in the coastal region of British Columbia and four in the Lower St. Lawrence region of Quebec. The NBC includes prescriptive solutions that call for the use of strong portions of walls called braced wall panels. Requirements for location, spacing, dimensions, fasteners and construction materials must be met, and these solutions are subject to limitations based on building height and whether the construction is comprised of heavy materials such as concrete roof tiles or concrete topping on floors. In addition, buildings in the high exposure category must also address concerns such as foundation anchorage, sheathing thickness, and sheathing and drywall fastener lengths and spacings. Lumber sheathing, if used, must be installed diagonally on both walls and roofs. Obtaining an engineered design is also an option.
Extreme Exposure Category Buildings in the extreme exposure category must be engineered. Only one of all the locations identified in NBC Appendix C falls into this category for wind, but three locations do in terms of earthquake exposure.
RESISTANCE TO LATERAL LOADS DUE TO WIND AND EARTHQUAKE Different areas of Canada are subject to varying risks of forces from winds and earthquakes. As a result, all buildings must be built to resist these lateral loads. The NBC Appendix C, Climatic and Earthquake Information for Building Design in Canada, provides wind pressures and earthquake factors used to determine exposure to wind and seismic (earthquake) loads for buildings. NBC 9.23 provides requirements for resisting lateral loads for low-rise buildings. The requirements are based on three levels of risk: low to moderate; high; and extreme.
Low to Moderate Exposure Category Buildings in the low to moderate exposure category provide resistance to wind and earthquake loads if they are of traditional wood-frame construction comprised of exterior sheathing, panel-type cladding or gypsum board finish. If two or more of these options are chosen, lateral load resistance will be increased. Of the 680 locations identified in NBC Appendix C, 671 and 630 locations fall into this category for wind and earthquake exposure respectively. This means that for most locations in Canada, bracing requirements can be met by using standard wood-framing materials and fastening
methods. One can also opt to design according to NBC Part 4 or follow good engineering practices such as those in the Engineering Guide for Wood Frame Construction 2009 published by the Canadian Wood Council.
High Exposure Category Buildings in the high exposure category require additional features to provide the required resistance to lateral loads. Nineteen locations identified in NBC Appendix C fall into this category for wind and 33 for earthquake exposure. For wind, affected locations are in Newfoundland, Quebec, Alberta, Nunavut and the Northwest Territories. Most of the locations affected by earthquake risk are in the coastal region of British Columbia and four in the Lower St. Lawrence region of Quebec. The NBC includes prescriptive solutions that call for the use of strong portions of walls called braced wall panels. Requirements for location, spacing, dimensions, fasteners and construction materials must be met, and these solutions are subject to limitations based on building height and whether the construction is comprised of heavy materials such as concrete roof tiles or concrete topping on floors. In addition, buildings in the high exposure category must also address concerns such as foundation anchorage, sheathing thickness, and sheathing and drywall fastener lengths and spacings. Lumber sheathing, if used, must be installed diagonally on both walls and roofs. Obtaining an engineered design is also an option.
Extreme Exposure Category Buildings in the extreme exposure category must be engineered. Only one of all the locations identified in NBC Appendix C falls into this category for wind, but three locations do in terms of earthquake exposure.
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